вопрос не дает мне покоя.
тема рискует сейчас перейти в разряд народного целительства, вот что я нашел на забугорном форуме:
"if the 'turning the frame upside down and clamping the seatpost in a vice whilst using the frame as a lever to free the post' method seems a bit too brutal, there is a secret freeing agent that works wonders on things like stuck seatposts and stems. this wonder potion is called 'coca-cola', yes it's true! but it has to be genuine coke. i've never known another 'coke' brand work. it works better than any lubricant/freeing agent. to apply it to a seatpost isn't too easy though as you need to leave it to soak in. the ideal way is to remove the bottom bracket and pour coke in through the b.b shell so it runs up the seat tube. leave it to soak in for as long as it needs, if it won't free up (it should) try the 'clamping the post in a vice' method after it's been soaked in coke. i don't know why it works but it does (watch it not work now!). it makes you wonder what coke might do to your insides!"
Если кратко перевести - залить кока колой на сутки и ждать что произойдет чудо.
К сожалению ветка так и не получила ответа от автора если такой способ ему помог.
Ниже есть фото на котором если не ошибаюсь именно ваш байк, с точно такой же проблемой.